Method of purifying perfluorocarbons, and use of the perfluorocarbons thus purified

Abstract

Described is a method for the purification of perfluorocarbons, or mixtures of perfluorocarbons, having impurities containing hydrogen and/or carbon-carbon double bonds. The impure perfluorocarbons or perfluorocarbon mixtures are reacted with strong aqueous bases in the presence of Ca 2+ or Ba 2+ ions and alcoholate ions together with secondary amines.

I claim: 
     
       1. Process for purification of perfluorocarbons or perfluorocarbon mixtures with hydrogen-containing or carbon-carbon double bond-containing impurities, characterized by the fact that the perfluorocarbons or perfluorocarbon mixtures to be purified are reacted with strong aqueous bases in the presence of Ca 2+   or Ba 2+   ions and alcoholate ions as well as secondary amines. 
     
     
       2. Process according to claim 1, characterized by the fact that the perfluorocarbons to be purified are reacted with the reactants in a homogeneous phase. 
     
     
       3. Process according to claim 1, characterized by the fact that a mixture consisting of a perfluorocarbon/aqueous base phase and an alcohol/secondary amine phase is homogenized by means of a surfactant. 
     
     
       4. Process according to claim 1, characterized by the fact that the reaction mixture is autoclaved at temperatures of 150°-200° C. 
     
     
       5. Process according to one of claim 1, characterized by the fact that the reaction mixture is autoclaved at pressures of 5-20 bar. 
     
     
       6. Process according to one of claim 1, characterized by the fact that the reaction mixture is boiled with reflux at normal pressure. 
     
     
       7. Process according one of claim 1, comprising forming the alcoholate ions by the addition of monofunctional alcohol to strong bases which further react as strong nucleophiles with fluoroolefins formed by HF elimination. 
     
     
       8. Process according to claim 7, wherein the monofunctional alcohol is designated ROH in which R is selected from the group consisting of CH 3 , C 2  H 5 , C 3  H 7 , and (CH 3 ) 2  CH. 
     
     
       9. Process according to one of claim 1, characterized by the fact that surfactants that are stable at the prevailing process conditions are used for homogenizing the reaction mixture. 
     
     
       10. Process according to claim 9, characterized by the fact that a surfactant known for the preparation of perfluorocarbons is used as the surfactant. 
     
     
       11. Process according to claim 1, characterized by the fact that surfactants from the group of fluorosurfactants that are stable in strongly alkaline media of the type R F  COOH or R F  SO 3  H (R F  ═CF 3  (CF 2 ) n , n═3-10) or their anions, R F  COO -   or R F  SO 3   - , are used. 
     
     
       12. Process according to claim 11, characterized by the fact that the surfactants are used in concentrations of 0.05-0.5, maximally 1.0 wt %. 
     
     
       13. Process according to claim 1, characterized by the fact that after completion of the entire purification process, the surfactant-containing aqueous alkaline phase is reused. 
     
     
       14. Process according to claim 1, characterized by the fact that the perfluorocarbons to be purified are reacted with the reactants in a "single-batch" process.